Marcus F. Cunliffe, 68, professor of American history at George Washington University, who was a noted author and a witty and incisive commentator on this country's history and literature, died September 2.

Dr. Cunliffe, a resident of Washington, D.C., had served on the George Washington University faculty since 1980 and was the second person to be appointed to the rank of University Professor since then.

He was the author of books that included both the popular and penetrating biography George Washington: Man and Monument, published in 1958, and The Literature of the United States, published in 1954 by Penguin Books in Britain.

The latter book was the beginning of Dr. Cunliffe's enviable reputation as a writer, teacher, and something of a father of interdisciplinary American studies in his native Britain.

Dr. Cunliffe said he became interested in America from seeing American films as a child, reading the works of Stephen Crane and James Thurber in school, and watching Americans fight during World War II. In addition to his research, he also maintained a lively interest in the work and lives of former students and colleagues. His interests spanned intellectual horizons and his works were not contained by the narrow boundaries of academic disciplines.

He wrote on the American presidency and slavery, as well as several books for children. His 1968 book Soldiers and Civilians: The Martial Spirit in American, 1775–1865 examined our society and the military. He was also co-editor of Pastmasters: Some Essays on American Historians.

It may have been the figure of George Washington that most intrigued him. In addition to his noted one-volume study, he was co-author of a juvenile work about the country's first president. In 1962 he edited a new edition of the classic Life of Washington by M.L. Weems.

Dr. Cunliffe was an intelligence officer in the British army's Royal Tank Regiment during World War II. A graduate of Oxford University's Oriel College, he studied as a Commonwealth Fund Fellow at Yale University from 1947 to 1949.

He taught at Manchester from 1949 to 1965, then at the University of Sussex until 1980. During those years he also spent time as a visiting professor at Harvard and Stanford Universities, as well as at the University of Michigan. He was a fellow at the Woodrow Wilson International Center in Washington in 1977 and 1978.

Survivors include his wife, Phyllis Palmer of Washington; three children by his first marriage, Antonia Cunliffe Davis of Birmingham, England, and Jason and Shay Cunliffe, both of New York City; and four grandchildren.